Electrode mounting apparatus for furnaces



United States Patent() ELECTRODE MOUNTING APPARATUS FOR FURNACES Herbert M Augsburger, Sylvania, Ohio, assignor to Owens-Illinois Glass Company, a corporation of Ohio This invention relates generally to an apparatus for introducing a resistance element or electrode into a heat zone, for example, a furnace. This invention relates more particularly to an improved mounting "apparatus of the character described which accomplishes the aforesaid more efficiently, allows greater economy of operation, and is in accord with the objects more specifically enumerated hereinafter.

conventionally, the introduction of a resistance element or electrode into a glass melting furnace is attended with many problems and disadvantages. With conventional arragements, the innermost parts of the electrode mounting structure are not visible to the operator of the furnace or to the maintenance crews in attendance. Furthermore, conventional arrangements have been subject to overheating through the entire length of the electrode, thus effecting rapid deterioration of the entire electrode by the resulting oxidative effects. Another disadvantage of conventional arrangements heretofore employed is the extreme likelihood of the electrode completely burning out by the aforesaid oxidative effects, resulting in the leaking of the contents of the furnace through the electrode introducing apparatus or, in the case of glass furnaces, the plugging-up of the electrode introducing aperture of the furnace wall.

It is, therefore, an object of this invention to provide an improved electrode mounting apparatus which allows visual observation of the interior thereof.

Another object of this invention is to provide an electrode mounting apparatus which permits the convenient introduction of a coolant within the electrode mounting apparatus.

Still another object of this invention is to provide an electrode mounting apparatus which insures continued use of the electrode aperture in the furnace wall, permits ready adjustment of the electrode penetration into the interior of the furnace, and confines deterioration effects to a localized portion of the electrode element.

More specific objects and advantages are apparent from the following description in which reference is had to the accompanying drawings, illustrating a preferred embodi ment of the invention.

Fig. 1 is a cross-sectional view of an electrode mounting embodying this invention, positioned in the wall of a heat vessel or furnace.

Fig. 2 is a sectional view taken on the plane 2-2 of Fig. 1.

Fig. 3 is an enlarged cross-sectional view of a portion of the electrode mounting apparatus of this invention, and particularly illustrating a specific embodiment thereof.

The electrode mounting apparatus embodying this invention basically comprises a tubular housing defining an electrode centering support at its inner end, a cap bushing attachable to the outer end, which includes a gasketed sight glass, thus defining a viewable coolant chamber, and an interiorly positioned electrode support, said tubular housing also being provided with coolant ingress and egress ports and arrangements for directing coolant along the length of the cooling chamber and terminating ad jacent to the furnace end of said tubular housing.

Referring specifically to the drawings, the reference numeral 1 schematically represents the wall of a high temperature furnace, such as a glass melting furnace, and such wall is supplied with an electrode aperture 1 at a level below its molten contents 2. A bracket 15 having a ring portion 15 concentric with furnace aperture 1 is suitably mounted adjacent to the furnace wall 1. A set screw 16 is positioned on the outer periphery of said ring portion 15 and projects through said ring portion to clamp the hereinafter described electrode mounting apparatus of this invention, and thereby prevent a pushing-out of the electrode mounting apparatus by the fluid pressure head of the molten contents within the furnace, The elecrode mounting apparatus 20 embodying this m vention is mounted in and supported by bracket 15 and the set screw 16 and, in turn, provides support for a rod-like electrode 10 which is connected to a suitable source of power by conducting band 11 having flanged ends 12 secured together by bolt and nut means 13, which also serves to secure an electrical lead wire 14. Electrode 10 extends through the furnace wall 1 into the interior of the furnace, and its inner end is thus surrounded by the molten contents 2 of the furnace.

Referring now specifically to the electrode mounting apparatus-20 of this invention, such is composed of a tubular housing 21 snugly insertable in furnace aperture 1 and having radial ports 22, 23, and 24 on its side wall.

To the port 22 is threadably connected a coolant inlet tube ,member 51. On the inner side of the tubular housing 21 over the port 22 is mounted a support post 52 having a passageway 57 which communicates with the port 22. Sealably connected to the passageway 57 is a tubular conduit member 53. This tubular conduit 53 extends linearly along the length of the tubular housing 21 and terminates at a point 54 near the extreme inner end of the apparatus 20. A tubular member 55 is threadably attached to the port 23 providing a coolant outlet. The port 24 is sealed with a threadably engaging plug 56, but serves a purpose hereinafter described. In another embodiment of this invention, as particularly illustrated in Fig. 3, the tubular conduit member 53 is sealably connected to a hollow ring member 58, having a plurality of equi-spaced ports or orifices 59. The ring member 58 encircles the electrode element 10 at the innermost end of the apparatus 20. The ports or orifices 59 are so positioned in the ring member 58 as to direct coolant at the point of contact of the electrode 10 and the plug type bushing 41, hereinafter described. This point of contact is represented'by the numeral 54. This particular arrangement provides a maximum degree of coolant efiicien'cy, particularly when the flow of coolant is in the direction illustrated in Fig. 1. While the aforesaid radial ports 22, 23, and 24 are illustrated linearly aligned in the tubular housing member 21,

they may obviously be displaced around the periphery I of said tubular housing member 21.

To the outer end of the tubular housing 21 is threadably attached an annular cap bushing 25. The cap bushing defin'es a hole 26 having an inside diameter approximately equal to the interior diameter of the tubular houshaving an inside Patented Dec. 23, 19581.

is positioned on the inner pe- 3 a weld 63. The bushing 41, by reason of its plug-type configuration, also engages the inner surface of the furnace wall aperture 1 and thus supports and centers the electrode 10 in concentric relation with the tubular housing 20. The plug-type configuration avoids detrimental contact between the molten contents 2 of the furnace and the weld 63. The bushing member 41 is preferably formed from a paramagnetic material having a permeability approaching unity, as distinguished from ferromagnetic materials having permeability values substantially greater than unity. Materials of the latter category are undesirable due to the fact that they are subject to having a current induced in them by the flow of electric current through the rod-like electrode. Induced current flow of this type results in hysteresis loss of current which would otherwise be directed to the heating area of the electrode, and also results in heat build-up within such materials, promoting deterioration thereof. The foregoing also ap plies with respect to the tubular housing member 21, but is most applicable to the bushing member 41 in view of its close proximity both to the electrode element 10 and the elevated furnace interior temperatures. As indicated hereinbefore, the inside diameter of the plug-type bushing member attache-d to the furnace end of the tubular housing member is maintained so as to be only slightly greater than the outside diameter of the electrode element 10. The close tolerance maintained between said bushing and the electrode, in conjunction with the coolant provisions, serves to insure the formation of a solid glass interface 65 within the area 64, as more clearly illustrated in Fig. 3. This interface serves to prevent any molten glass from entering the coolant chamber 62 of the tubular housing 20.

Diametrically opposite the support post 52, there is positioned an externally adjustable set screw 61, which extends through the wall of the tubular housing 21 to contact the surface of the electrode 10 and secure it firmly between the set screw and the interiorally positioned support post 52.

Typical operating procedure would involve introducing the electrode 10 through the aperture defined by the gasket 30', through the interior passageway of the tubular housing 21, snugly but slideably through the aperture of the bushing 41, and thence into the interior of the furnace. When the desired length of electrode has been introduced, the set screw 61 may be adjusted to secure the electrode 10 against the support post 52. It has been demonstrated that the electrode may be initially introduced to a greater depth of penetration than will be maintained in normal operation. This initial penetration will allow a coating of a glass to adhere to a peripheral section of the electrode which, when the electrode is retracted slightly into operating position, will provide a coating of glass within the area defined between the plug-type bushing 41 and the electrode 10, thus providing an additional safety factor against molten glass flow from the furnace into the coolant chamber 62. As illustrated in Fig. 2, the coolant may enter through the tubular member 51 and will be directed through the passasgeway 57 of the support post 52, the tubular conduit 53, and thus directed to the extreme inner end of passageway 62. The coolant will fill the passageway 62. and will flow out through the port 23 and the tubular member 55. The flow of the coolant as just described is preferred because it confines deteriorationv to the shortest possible length of the electrode. However, under other conditions, the flow may be desirably carried out in the reverse direction, as shown for purpose of illustration in Fig. 3. The coolant may be any suitable fiu id, such as water, oil, argon, helium, manufactured gas, etc. In the operation of a glass furnace, where the temperatures inside of the furnace may range from 2000 F. to 3000 F., it has been found that water may conveniently be utilized as the coolant and, further, that the temperature of the water Within the electrode mounting apparatus can be held between 130 F. to 140 F. With an inert gas as the coolant, the temperature within the electrode mounting apparatus can be held to about 500 F. The

temperature differential, or gradient, between the interior of the furnace (2000 F. to 3000 F.) and the electrode mounting apparatus F. to 700 F.) is thus affected by the proper choice of coolant, direction of flow of coolant, and rate of flow of coolant. A proper gradient serves to prevent any of the molten glass from entering the electrode mounting apparatus, for the glass solidifies some where in the area 64 between the bushing 41 and the electrode 10, as hereinbefore described. In any event, the molten glass does not enter the interior of the electrode mounting apparatus.

As illustrated in the accompanying. drawings, the electrode and electrode mounting apparatus are shown in a typical horizontal installation. The same electrode and electrode mounting assembly could be positioned to pro ject vertically into the furnace. In such installation, the outlet tube 55 and the plug 56 could. be interchanged in the respective ports 23 and 24, depending upon the height of fluid reservoir desired in the electrode mounting apparatus.

As can be readily appreciated, the sight glass 29 in the outer end of the electrode mounting apparatus permits the interior of the electrode mounting apparatus to be readily observed. This permits the operator or the main? tenance crew to check the condition of the coolant-directing orifice at any time, and to anticipate any clogging, plugging-up, or deterioration thereof. Ready observancev of the interior of the electrode mounting apparatus is also very important at the time that it becomes necessary to adjust the electrode penetration. Thus, when the external manifestations of the furnace operation indicate insufficient heating due to insufficient power, an adjustment of electrode penetration in the furnace is made to return the furnace to efficient operating condition- Normally, when the electrode penetration is to be adjusted, the coolant flow is terminated. After this adjustment, which involves. penetration followed by a slight retraction as more particularly described hereinbefore, the resumption of coolant fiow can be accurately timed and gauged by viewing the internal condition of the electrode mounting apparatus as provided by the sight glass feature. inherent in the novel. apparatus of this invention.

Although this invention has been described with particular reference to certain preferred embodiments thereof, it is obviously possible to make variations and modifications thereon without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. An apparatus for mounting a rod-like electrode in a furnace wall aperture, comprising a tubular housing insertable in said aperture, means. on the inner end of said housing for slideably supporting said electrode in concentric relation therewith, an annular sight. glasshaving a central aperture to receive said electrode, gasket. means for mounting said annular sight glass at the outer end. of said housing in fluid-sealed relationship with said housing and electrode, thereby defining a viewable chamber, and means for supplying coolant. to. said chamber.

2. An apparatus for mounting a rod-like. electrode in a furnace wall aperture, comprising. a tubular. housing insertable in said aperture, means on the. inner end of said.

housing for slideably supporting said electrode. in concentric relation therewith, an annular cap bushing attachable:

' to the outer end of said housing and. including an annular sight glass having a central aperture. to receive said. electrode, separate gasket means'positioned on the inner. and. outer periphery of said annular sight glass for mounting said sight glass between said housing and said cap bushing in fluid-sealed relationship respectively with said housing and electrode, thereby defining a viewable chamber, and means for supplying coolant to said chamber.

3. An apparatus for mounting a rod-like. electrode. in a furnace wall aperture, comprising; a tubular housing" insertable said aperture and having, a plurality of. coolant parts in the radial wall of said housing, means on the inner end of said housing for slideably supporting said electrode in concentric relation therewith, an annular sight glass having a central aperture to receive said electrode, gasket means for mounting said annular sight glass at the outer end of said housing in fluid-sealed relationship with said housing and electrode, thereby defining a viewable chamber, a support post mounted on the inner radial wall of said housing over one of said ports, said support post defining a fluid passageway communicating with said one port, and adjustable set screw means positioned on said housing diametrically opposite said support post and cooperating therewith to clamp said electrode.

4. An apparatus for mounting a rod-like electrode in a furnace wall aperture, comprising a tubular housing insertable in said aperture and having a plurality of coolant ports in the radial wall of said housing, means on the inner end of said housing for slideably supporting said electrode in concentric relation therewith, an annular sight glass having a central aperture to receive said electrode, gasket means for mounting said annular sight glass at the outer end of said housing in fluidsealed relationship with said housing and electrode, thereby defining a viewable chamber, a support post mounted on the inner radial wall of said housing over one of said ports, said support post having a fluid passageway communicating with said one port, conduit means extending from said support post to the furnace end of said housing, thereby directing coolant upon the electrode support means, and an adjustable set screw means traversing said housing wall diametrically opposite said support post and cooperating therewith to clamp said electrode.

5. In an apparatus for introducing a rod-like electrode into a furnace through a wall aperture, the combination of a tubular housing insertable in said aperture having a furnace end, an outer end, and two side ports for ingress and egress of a coolant, an annular cap bushing sealably attachable to the said outer end of said housing including an annular sight glass having a central aperture to receive said electrode, gasket means positioned between the outer radial end surface of said housing and said annular bushing, to sealably engage the outer periphery of said annular sight glass, gasket means positioned on the inner periphery of said annular sight glass to sealably engage said electrode, a bushing attached to the furnace end of said housing for slideably supporting said electrode in concentric relation therewith, a support post mounted on the inner wall of said housing over one of said ports, said support post having a fluid passageway communicating with said one port, and adjustable set screw means traversing said housing wall diametrically opposite said support post and cooperating therewith to clamp said electrode.

6. An apparatus for mounting a rod-like electrode in a furnace wall aperture comprising a tubular housing insertable in said aperture and having a plurality of ports in the radial wall of said housing, means on the inner end of said housing for slidably supporting said electrode in concentric relation therewith, an annular sight glass having a central aperture to receive said electrode, gasket means for mounting said annular sight glass at the outer end of said housing in fluid-sealed relationship with said housing and electrode thereby defining a viewable chamber, a conduit extending from one of said ports to the furnace end of said housing, and an electrode encircling hollow ring connecting with said conduit at the furnace end, said ring having a plurality of orifices aimed at the boundary between said electrode and said bushing.

7. An apparatus as claimed in claim 4, further characterized by the fact that the conduit means includes, connected thereto at the furnace end, an electrode encircling hollow ring having a plurality of orifices aimed at the boundary between said electrode and said bushing.

8. An apparatus as claimed in claim 5, further characterized by the fact that the bushing attached to the furnace end of said housing is constructed and arranged so as to encircle the electrode element and fill ,the annular space between said electrode and the inner surface of the furnace wall aperture whereby the said housing is not contacted by the furnace contents.

References Cited in the file of this patent UNITED STATES PATENTS 1,283,285 Pfanstiehl Oct. 29, 1918 1,880,806 Cioffi Oct. 4, 1932 2,736,759 Penberthy Feb. 28, 1956 

